Imaging device and electronic camera

ABSTRACT

An imaging device includes an arrayed imaging element group configured to receive light passing through a photographic lens, wherein the imaging element group includes a plurality of photographic elements used for photographic image data generation and a plurality of phase difference detection elements used for phase difference detection for focus detection of the photographic lens, each of the photographic elements and each of the phase difference detection elements include: an on-chip microlens configured to collect light passing through the photographic lens; a photoelectric conversion element configured to receive the light passing through the on-chip microlens; and an internal microlens disposed between the on-chip microlens and the photoelectric conversion element, the photographic element is configured such that an optical axis of the on-chip microlens matches an optical axis of the internal microlens, and the phase difference detection element is configured such that the optical axis of the on-chip microlens is shifted from the optical axis of the internal microlens.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The presently disclosed subject matter relates to an imaging devicehaving an imaging element group used for photographic image datageneration and an imaging element group used for phase differencedetection; and an electronic camera having the imaging device.

2. Description of the Related Art

There has been known an imaging device having a plurality of imagingelements (photographic elements) used for photographic image datageneration and a plurality of imaging elements (phase differencedetection elements) used for phase difference detection. Each imagingelement of this imaging device includes a photoelectric conversionelement (pixel). Moreover, a phase difference detection element groupincludes a first element group performing photoelectric conversion onobject light passing through one partial region of an exit pupil of aphotographic lens; and a second element group performing photoelectricconversion on object light passing through the other partial region ofthe exit pupil of the photographic lens. A defocus amount of thephotographic lens can be detected by detecting a phase differencebetween pixel information obtained by the first element group and pixelinformation obtained by the second element group.

Japanese Patent Application Laid-Open No. 2005-303409, Japanese PatentNo. 2959142, and Japanese Patent Application Laid-Open No. 59-15208disclose a structure in which a microlens is disposed shifted from aphotoelectric conversion element.

Japanese Patent Application Laid-Open No. 2008-71920 discloses astructure in which a microlens is disposed for a plurality ofphotoelectric conversion elements.

SUMMARY OF THE INVENTION

An arrayed configuration in which a plurality of photographic elementsand a plurality of phase difference detection elements are disposed on alight receiving surface can eliminate the need to use an optical pathdividing mechanism and a distance measuring sensor and thus achieve lowcosts and space saving as well as high-speed focus detection. However,further microfabrication reduces the amount of light incident on aphotoelectric conversion element. In particular, the phase differencedetection element group performs photoelectric conversion on objectlight passing through a partial region of the exit pupil of thephotographic lens, and thus a reduction in incident light causes aremarkable reduction in focus detection precision.

Note that as disclosed in Japanese Patent Application Laid-Open No.2008-71920, when a microlens is disposed for a plurality ofphotoelectric conversion elements for phase difference detection, thefocal length of the microlens increases and thus it is difficult todispose the photoelectric conversion elements for phase differencedetection and the photoelectric conversion element for photographing onthe same plane. Moreover, when the photoelectric conversion elements fora microlens are divided into one for phase difference detection and onefor photographing, further microfabrication makes it difficult to forman opening thereof in such a manner that one for guiding light into thephotoelectric conversion element for phase difference detection issmaller than one for the photoelectric conversion element forphotographing. Moreover, the amount of light incident on a photoelectricconversion element is reduced remarkably.

Further, if an internal structure is made differently between thephotographic element and the phase difference detection element, it isdifficult to reuse the internal structure for ordinary imaging device,causing another problem with an increase in manufacturing cost in theentire business. Furthermore, the photoelectric conversion element(pixel) for phase difference detection is subject to a restriction in alight receiving direction and thus it is difficult to use the pixelinformation to generate high-quality photographic image data. Stillfurthermore, when phase difference detection elements are disposed athigh density in order to ensure focus detection precision at lowintensity, the photographic image quality deteriorates. Thus, what isneeded is to achieve a good balance between an improvement in imagequality of photographic image data and an improvement in focus detectionprecision.

In view of such circumstances, the presently disclosed subject matterhas been made, and an object of the presently disclosed subject matteris to provide an imaging device and an electronic camera which canachieve low costs, space saving, and high-speed focus detection as wellas accurate focus detection even with microfabrication.

In order to achieve the above object, the presently disclosed subjectmatter provides an imaging device having an arrayed imaging elementgroup which receives light passing through a photographic lens, whereinthe imaging element group includes a plurality of photographic elementsused for photographic image data generation and a plurality of phasedifference detection elements used for phase difference detection forfocus detection of the photographic lens, each of the photographicelements and each of the phase difference detection elements include: anon-chip microlens which collects light passing through the photographiclens; a photoelectric conversion element which receives the lightpassing through the on-chip microlens; and an internal microlens whichis disposed between the on-chip microlens and the photoelectricconversion element, the photographic element is configured such that anoptical axis of the on-chip microlens matches an optical axis of theinternal microlens, and the phase difference detection element isconfigured such that the optical axis of the on-chip microlens isshifted from the optical axis of the internal microlens.

Briefly, an imaging element includes an on-chip microlens, an internalmicrolens and a photoelectric conversion element as well as a phasedifference detection element is configured such that an optical axis ofthe on-chip microlens is shifted from the optical axis of the internalmicrolens. This configuration can efficiently introduce light passingthrough a partial region of an exit pupil of the photographic lens intothe photoelectric conversion element in comparison with a configurationin which the on-chip microlens is only shifted from the photoelectricconversion element without providing an internal microlens. Thus, thepresently disclosed subject matter can achieve low costs, space saving,and high-speed focus detection as well as accurate focus detection evenwith microfabrication.

According to an aspect of the presently disclosed subject matter, boththe photographic element and the phase difference detection element areconfigured such that the optical axis of the internal microlens matchesthe optical axis of the photoelectric conversion element.

Briefly, both the photographic element and the phase differencedetection element are configured such that the optical axis of theinternal microlens matches the optical axis of the photoelectricconversion element. Thus, a base side laminated structure (chip)including an internal microlens and a photoelectric conversion elementcan be shared with an ordinary imaging device.

Moreover, the presently disclosed subject matter provides an imagingdevice having an arrayed imaging element group which receives lightpassing through a photographic lens, wherein the imaging element groupincludes a plurality of photographic elements used for photographicimage data generation and a plurality of phase difference detectionelements used for phase difference detection for focus detection of thephotographic lens, each of the photographic elements and each of thephase difference detection elements include: an on-chip microlens whichcollects light passing through the photographic lens; a photoelectricconversion element which receives the light passing through the on-chipmicrolens; and an internal microlens which is disposed between theon-chip microlens and the photoelectric conversion element and has anentrance lens on an upstream side of an optical path and an exit lens ona downstream side of the optical path, the photographic element isconfigured such that an optical axis of the entrance lens of theinternal microlens matches an optical axis of the exit lens, and thephase difference detection element is configured such that the opticalaxis of the entrance lens of the internal microlens is shifted from theoptical axis of the exit lens.

Briefly, an imaging element includes an on-chip microlens, an internalmicrolens and a photoelectric conversion element as well as a phasedifference detection element is configured such that the optical axis ofthe entrance lens of the internal microlens is shifted from the opticalaxis of the exit lens. This configuration can efficiently introducelight passing through a partial region of an exit pupil of thephotographic lens into the photoelectric conversion element incomparison with a configuration in which the on-chip microlens is onlyshifted from the photoelectric conversion element without providing aninternal microlens. Thus, the presently disclosed subject matter canachieve low costs, space saving, and high-speed focus detection as wellas accurate focus detection even with microfabrication.

According to an aspect of the presently disclosed subject matter, boththe photographic element and the phase difference detection element areconfigured such that the optical axis of the exit lens of the internalmicrolens matches the optical axis of the photoelectric conversionelement.

Briefly, both the photographic element and the phase differencedetection element are configured such that the optical axis of the exitlens of the internal microlens matches the optical axis of thephotoelectric conversion element. Therefore, an electrode arrangementfor reading pixel information can be shared between the photographicelement and the phase difference detection element. Thus, furthermicrofabrication is enabled.

According to an aspect of the presently disclosed subject matter, thephotoelectric conversion element of the phase difference detectionelement has the same shape as that of the photoelectric conversionelement of the photographic element.

According to an aspect of the presently disclosed subject matter, theon-chip microlens of the phase difference detection element has asmaller diameter than the diameter of the on-chip microlens of thephotographic element.

Briefly, this configuration can prevent the on-chip microlens of thephase difference detection element from interfering with the on-chipmicrolens of the photographic element.

According to an aspect of the presently disclosed subject matter, alight shielding unit is provided around the on-chip microlens of thephase difference detection element.

Thus, the configuration can prevent unnecessary light from entering thephotoelectric conversion element.

An aspect of the presently disclosed subject matter provides a first anda second of the phase difference detection elements which generate pixelinformation corresponding to light passing through mutually differentpartial regions of the exit pupil of the photographic lens, wherein amutually adjacent pair of elements including the first and the second ofthe phase difference detection elements is arranged in an array pattern.Moreover, according to an aspect of the presently disclosed subjectmatter, three or more of the photographic elements having a color filterof the same color are arranged adjacent to each of the phase differencedetection elements. Further, an aspect of the presently disclosedsubject matter provides an image data generation device which generatesphotographic image data based on pixel information read from thephotographic element, namely, an image data generation device whichgenerates the photographic image data by interpolation based on pixelinformation read from the photographic elements having a color filter ofthe same color are arranged adjacent to each of the phase differencedetection elements.

Thus, an adjacent arrangement of the first and second phase differencedetection elements increases the correlation of pixel information forphase difference detection and improves focus detection precision.Further, high-quality photographic image data is generated byinterpolating the pixel information for photographic image datageneration in each pixel position for phase difference detection basedon photographic pixel information of three or more photographic elementsadjacent to each of the phase difference detection elements.

An aspect of the presently disclosed subject matter provides a first anda second of the phase difference detection elements which generate pixelinformation corresponding to light passing through mutually differentpartial regions of the exit pupil of the photographic lens, wherein amutually adjacent pair of elements including the first and the second ofthe phase difference detection elements is arranged in a staggeredpattern.

Thus, an adjacent arrangement of the first and second phase differencedetection elements and a staggered arrangement thereof improve focusdetection precision.

An aspect of the presently disclosed subject matter provides a first anda second of the phase difference detection elements which generate pixelinformation corresponding to light passing through mutually differentpartial regions of the exit pupil of the photographic lens, wherein afirst element pair including a mutually adjacent pair of the first phasedifference detection elements and a second element pair including amutually adjacent pair of the second phase difference detection elementsare arranged in an array pattern.

Thus, focus detection precision at low intensity can be ensured byperforming pixel information synthesis (pixel mixing) on a mutuallyadjacent pair of first phase difference detection elements as well as byperforming pixel information synthesis (pixel mixing) on a mutuallyadjacent pair of second phase difference detection elements.

An aspect of the presently disclosed subject matter provides a first anda second of the phase difference detection elements which generate pixelinformation corresponding to light passing through mutually differentpartial regions of the exit pupil of the photographic lens, wherein amutually adjacent element pair including the first and second phasedifference detection elements is arranged in an array pattern along afirst direction for phase difference detection and along a seconddirection for synthesizing the pixel information, and an arrangementpitch of the element pair in the first direction is equal to or lessthan arrangement pitch of the element pair in the second direction.Further, an aspect of the presently disclosed subject matter provides afocus detection device which synthesizes pixel information of thephotoelectric conversion element between a plurality of the first phasedifference detection elements arranged along the second direction aswell as synthesizes pixel information of the photoelectric conversionelement between a plurality of the second phase difference detectionelements arranged along the second direction, and performs focusdetection of the photographic lens based on the synthesized pixelinformation.

Thus, focus detection precision can be ensured by increasing the densityof the phase difference detection elements in the first direction forphase difference detection as well as focus detection precision can beensured by pixel information synthesis (pixel mixing) in the seconddirection even with a reduced density of the phase difference detectionelements.

Thus, the presently disclosed subject matter can achieve low costs,space saving, and high-speed focus detection as well as accurate focusdetection even with microfabrication.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a schematic configuration of anexample of a digital camera according to the presently disclosed subjectmatter;

FIG. 2 is a plan view illustrating an example of an imaging unit with aBayer array;

FIG. 3 is a sectional view illustrating a part of a cross section alongthe line 3-3 in FIG. 2;

FIG. 4 is a plan view illustrating an example of an imaging unit with ahoneycomb configuration;

FIG. 5 is a sectional view illustrating a phase difference detectionelement according to a first embodiment;

FIG. 6 is a plan view illustrating an example of an imaging unitaccording to a second embodiment;

FIG. 7 is a sectional view illustrating a phase difference detectionelement according to a third embodiment;

FIG. 8 is a sectional view illustrating a phase difference detectionelement according to a fourth embodiment;

FIG. 9 is a sectional view illustrating a phase difference detectionelement according to a fifth embodiment;

FIG. 10 is a plan view illustrating an element arrangement of an imagingunit according to a sixth embodiment;

FIG. 11 is a plan view illustrating an element arrangement of an imagingunit according to a seventh embodiment;

FIG. 12 is a plan view illustrating an element arrangement of an imagingunit according to an eighth embodiment;

FIG. 13 is a plan view illustrating an element arrangement of an imagingunit according to a ninth embodiment;

FIG. 14 is a plan view illustrating an example of a double facedhoneycomb configuration;

FIG. 15 is a plan view describing pixel information interpolation on anelement array plane “A” in FIG. 14;

FIG. 16 is a plan view describing pixel information interpolation on anelement array plane “B” in FIG. 14;

FIG. 17 is a plan view illustrating an example of a double faced Bayerarray;

FIG. 18 is a plan view describing pixel information interpolation on anelement array plane “A” in FIG. 17;

FIG. 19 is a plan view describing pixel information interpolation on anelement array plane “B” in FIG. 17; and

FIG. 20 is a schematic flowchart illustrating a flow of an example of aphotographing process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, by referring to the accompanying drawings, embodiments ofthe presently disclosed subject matter will be described in detail.

FIG. 1 is a block diagram illustrating a schematic configuration of anexample of a digital camera according to the presently disclosed subjectmatter.

In FIG. 1, a digital camera 100 according to the present embodimentincludes: a photographic lens 40, a lens drive unit 41, an imaging unit42, an imaging control unit 43, an analog signal processing unit 44, animage input controller 45, a memory 46, a CPU (central processing unit)50, a digital signal processing unit 61, a compression/expansionprocessing unit 62, a recording medium control unit 63, a recordingmedium 64, a display control unit 65, a display unit 66, and anoperation unit 67.

The photographic lens 40 includes a zoom lens and a focus lens. The lensdrive unit 41 moves a lens constituting the photographic lens 40 in adirection of an optical axis O.

The imaging unit 42 takes an image by receiving object light passingthrough the photographic lens 40. The imaging unit 42 according to thepresent embodiment is configured of a CCD (Charge Coupled Device)imaging device and includes an imaging element used for photographicimage data generation (hereinafter also referred to as a “photographicelement”) and an imaging element used for phase difference detection forfocus detection of the photographic lens 40 (hereinafter also referredto as a “phase difference detection element”). Specific examples of thephotographic element and the phase difference detection element will bedescribed in detail later.

The imaging control unit 43 controls charge accumulation in thephotographic element and the phase difference detection element andcontrols reading pixel information from the photographic element and thephase difference detection element.

The analog signal processing unit 44 performs various analog signalprocessing (noise removal, amplification, etc.) on a pixel signal (pixelinformation) outputted from the imaging unit 42. The analog signalprocessing unit 44 has an A/D converter which converts a pixel signalfrom analog to digital.

The image input controller 45 stores a digital pixel signal outputtedfrom the analog signal processing unit 44 in the memory 46.

The CPU (Central Processing Unit) 50 controls each unit of the digitalcamera 100 by executing a predetermined program.

The digital signal processing unit 61 performs various digital signalprocessing (e.g., tone characteristics processing, sharpness processing,white balance adjustment, YC signal generation, etc.) on pixelinformation stored in the memory 46 in response to an instruction fromthe CPU 50.

The compression/expansion processing unit 62 compresses various data andexpands various data in response to an instruction from the CPU 50.

The recording medium control unit 63 controls recording various data inthe recording medium 64 and acquiring various data from the recordingmedium 64 in response to an instruction from the CPU 50. The recordingmedium 64 is not particularly limited, but, for example, a memory cardattachable to and detachable from the main body of the digital camera100 is used.

The display control unit 65 controls displaying on the display unit 66in response to an instruction from the CPU 50. The display unit 66 is adevice capable of displaying an image, and for example, includes aliquid crystal display.

The operation unit 67 is an instruction input device through which theuser inputs various instructions to the digital camera 100. For example,the operation unit 67 includes a shutter button and a mode switchingswitch.

The CPU 50 according to the present embodiment includes a focusdetection unit 51, a focusing control unit 52, and an image datageneration unit 53.

The focus detection unit 51 performs focus detection by a phasedifference detection method based on pixel information read from a phasedifference detection element of the imaging unit 42. The focus detectionmethod may be the same method disclosed in Japanese Patent No. 4007716or Japanese Patent Application Laid-Open No. 59-15208.

The focusing control unit 52 performs focusing based on a focusdetection result of the focus detection unit 51. More specifically, thefocusing control unit 52 causes the lens drive unit 41 to move a focuslens constituting the photographic lens 40 to a focusing lens positionin which the object is focused as needed.

The image data generation unit 53 generates photographic image databased on pixel information read from a photographic element of theimaging unit 42. The generated photographic image data is compressed bythe compression/expansion processing unit 62 and is recorded in therecording medium 64 by the recording medium control unit 63. Inaddition, the photographic image data can be displayed on the displayunit 66 as a photographic image by the display control unit 65.

FIG. 2 is a plan view illustrating a part of an example of an imagingunit (42 in FIG. 1) with a Bayer array. FIG. 3 is a sectional viewillustrating a part of a cross section along the line 3-3 in FIG. 2.

As illustrated in FIG. 2, a first imaging element 11 (photographicelement) used for photographic image data generation, a second imagingelement 12 a (a first phase difference detection element) used for phasedifference detection, and a third imaging element 12 b (a second phasedifference detection element) are arranged in an array pattern on alight receiving surface (paper in FIG. 2) which receives object lightpassing through a photographic lens (40 in FIG. 1). Note that in fact, alarge number of imaging elements 11, 12 a, and 12 b are arranged on thelight receiving surface.

Each of the imaging elements 11, 12 a, and 12 b includes respective topmicrolenses 13, 14 a, and 14 b formed on an uppermost surface of alaminated structure 110 (chip) (also referred to as “on-chipmicrolens”), respective inner microlenses 15, 16 a, and 16 b formedinside the laminated structure 110 (also referred to as “internalmicrolens”), and respective photodiodes 17, 18 a, and 18 b performingphotoelectric conversion (also referred to as “photoelectric conversionelement”).

Each of the top microlenses 13, 14 a, and 14 b collects light passingthrough the photographic lens 40. Each of the inner microlenses 15, 16a, and 16 b collects light passing through each of the respective topmicrolenses 13, 14 a, and 14 b. Each of the photodiodes 17, 18 a, and 18b receives light passing through each of the respective inner microlens15, 16 a, and 16 b and accumulates a signal charge corresponding to theamount of received light. The accumulated signal charge is read as pixelinformation for each of the imaging elements 11, 12 a, and 12 b underthe control of the imaging control unit (43 in FIG. 1).

A group of the photodiodes 17 of the photographic element 11 collectslight passing through an entire region of the exit pupil of thephotographic lens 40. A group of the photodiodes 18 a of the first phasedifference detection element 12 a collects object light passing throughone partial region of the exit pupil of the photographic lens 40. Agroup of photodiodes 18 b of the second phase difference detectionelement 12 b receives object light passing through the other partialregion of the exit pupil of the photographic lens 40.

The imaging unit 42 according to the present embodiment is configuredsuch that a light shielding film 102, an insulating film 103, a lenslayer 104, a flat layer 105, and a color filter layer 106 are laminatedon a semiconductor substrate 101. Photodiodes 17, 18 a, and 18 b, and aVCCD 19 (vertical charge transfer path) are formed on the semiconductorsubstrate 101. The light shielding film 102 is formed on a regionseparating between the photodiodes 17, 18 a, and 18 b of an uppersurface of the semiconductor substrate 101. The insulating film 103 isformed of an insulating material having light transmissibility. Theinternal microlenses 17, 18 a, and 18 b are formed in the lens layer104. The flat layer 105 is formed of a light-transmissive material.Color filters of red (R), green (G), and blue (B) are formed in thecolor filter layer 106.

The photographic element 11 is configured such that the optical axis ofthe top microlens 13, the optical axis of the inner microlens 15, andthe optical axis of the photodiode 17 are matched. The relationshipamong the optical axis of the top microlenses 14 (14 a and 14 b), theoptical axis of the inner microlenses 15 (15 a and 15 b), and theoptical axis of the photodiodes 17 (17 a and 17 b) in the phasedifference detection elements 12 (12 a and 12 b) will be described indetail later separately in various embodiments.

Each of the top microlenses 14 a and 14 b of the respective phasedifference detection elements 12 a and 12 b according to the presentembodiment has a smaller diameter than the diameter of the top microlens13 of the photographic element 11. Moreover, each of the photodiodes 18a and 18 b of the respective phase difference detection elements 12 aand 12 b according to the present embodiment has the same shape as theshape of the photodiode 17 of the photographic element 11.

FIG. 4 is a plan view illustrating a part of an example of an imagingunit (42 in FIG. 1) with a honeycomb configuration. Note that in FIG. 4,the same reference numeral or character is assigned to the same elementas the element in a Bayer array illustrated in FIG. 2.

In the honeycomb configuration, photodiodes in even rows are shifted by½ pitch from photodiodes in odd rows.

Hereinafter, various imaging units 42 (imaging apparatuses) according tothe presently disclosed subject matter will be described for eachembodiment.

First, an imaging unit 42 according to a first embodiment will bedescribed. Note that what has been described by referring to FIGS. 2 to4 will be omitted here.

FIG. 5 is a sectional view illustrating a phase difference detectionelement 12 according to the first embodiment. As illustrated in FIG. 5,the phase difference detection element 12 according to the presentembodiment is configured such that the optical axis (central axis) ofthe top microlens 14 is shifted from the optical axis (central axis) ofthe inner microlens 16. In addition, the optical axis of the innermicrolens 16 is shifted from the optical axis of the photodiode 18.Further, the optical axis of the top microlens 14 is shifted from theoptical axis of the photodiode 18.

The present embodiment is configured such that the optical axis of thetop microlens 14 is shifted from the optical axis of the inner microlens16. Thus, the photodiode 18 can efficiently receive object light passingthrough a partial region of the exit pupil of the photographic lens 40,namely, the light whose light receiving direction is restricted.

Next, an imaging unit 42 according to a second embodiment will bedescribed. Note that what has been described in the first embodimentwill be omitted here.

FIG. 6 is a plan view illustrating a part of an example of the imagingunit 42 according to the present embodiment. The present embodimentillustrates a honeycomb configuration. As illustrated in FIG. 6, in thepresent embodiment, a light shielding unit for shielding light isprovided around the top microlenses 14 (14 a and 14 b) of the phasedifference detection elements 12 (12 a and 12 b). Note that thedescription is given on an example of the honeycomb configuration, but aBayer array may be used.

Next, an imaging unit 42 according to a third embodiment will bedescribed. Note that what has been described in the first and secondembodiments will be omitted here.

FIG. 7 is a sectional view illustrating a phase difference detectionelement 12 according to the present embodiment. As illustrated in FIG.7, in the phase difference detection element 12 according to the presentembodiment, the optical axis (central axis) of the inner microlens 16matches the optical axis (central axis) of the photodiode 18.

The phase difference detection element 12 according to the presentembodiment can be formed by shifting only the top microlens 14 on theupper surface of a laminated structure (110 in FIG. 3) in comparisonwith the photographic element 11. Thus, the laminated structure beforethe top microlens 14 is formed thereon can be easily shared by otherimaging devices conforming to a specification in which the phasedifference detection element 12 is not provided.

Next, an imaging unit 42 according to a fourth embodiment will bedescribed. Note that what has been described by referring to FIGS. 2 to4 will be omitted here.

FIG. 8 is a sectional view illustrating a phase difference detectionelement 12 according to the present embodiment. As illustrated in FIG.8, the phase difference detection element 12 according to the presentembodiment is configured such that the optical axis (central axis) ofthe entrance lens 161 of the inner microlens 16 is shifted from theoptical axis (central axis) of the exit lens 162. The entrance lens 161is a convex lens (upper convex lens) on an upstream side of the opticalpath, and the exit lens is a convex lens (lower convex lens) on adownstream side of the optical path.

Note that the present embodiment is further configured such that theoptical axis of the top microlens 14 is shifted from the optical axis ofthe entrance lens 161 of the inner microlens 16. Furthermore, theoptical axis of the entrance lens 161 of the inner microlens 16 isshifted from the optical axis of the photodiode 18.

The present embodiment is configured such that the optical axis of theexit lens 162 is shifted from the optical axis of the entrance lens 161of the inner microlens 16. Thus, the photodiode 18 for phase differencedetection can efficiently receive light passing through a restrictedpartial region of the exit pupil of the photographic lens 40.

Next, an imaging unit 42 according to a fifth embodiment will bedescribed. Note that what has been described in the fourth embodimentwill be omitted here.

FIG. 9 is a sectional view illustrating a phase difference detectionelement 12 according to the present embodiment. As illustrated in FIG.9, like the photographic element (11 in FIG. 3), in the phase differencedetection element 12 according to the present embodiment, the opticalaxis (central axis) of the inner microlens 16 matches the optical axis(central axis) of the photodiode 18.

Thus, the electrode arrangement for reading the charge accumulated inthe photodiode 18 out onto a vertical charge transfer path can be sharedbetween the photographic element 11 and the phase difference detectionelement 12. In other words, this configuration eliminates the need toshift the electrode for the phase difference detection element 12, andthus can achieve a high density arrangement of imaging elements.

Next, an imaging unit 42 according to a sixth embodiment will bedescribed. The present embodiment restricts an arrangement of the phasedifference detection element 12 according to any one of the first tofifth embodiments, and thus what has been described in the first tofifth embodiments will be omitted here.

FIG. 10 is a plan view illustrating an element arrangement of an imagingunit 42 according to a sixth embodiment. As illustrated in FIG. 10, inthe present embodiment, phase difference detection element pairs 31having a mutually adjacent first phase difference detection element 12 aand second phase difference detection element 12 b are arranged in anarray pattern along the horizontal direction H which is a phasedifference detection direction.

In FIG. 10, each of R, G, and B designates a color of the color filter.The photographic element 11 has a color filter of R (red), G (green) orB (blue), and the phase difference detection elements 12 (12 a and 12 b)has a color filter of G. In addition, three photographic elements 11having a color filter of the same color (G in the present embodiment)are arranged adjacent to each phase difference detection element 12. One(e.g., 11 a) of the photographic elements 11 is located between thephase difference detection element pairs 31. For example, thephotographic element 11 a of the photographic elements 11 a, 11 b, and11 c is located between the first phase difference detection elements 12a, and the photographic element 11 d of the photographic elements 11 d,11 e, and 11 f is located between the second phase difference detectionelements 12 b.

According to the present embodiment, when the image data generation unit(53 in FIG. 1) interpolates pixel information for photographic imagedata generation in a pixel position of each phase difference detectionelement 12, the image data generation unit uses pixel information of thethree photographic elements 11 having a color filter of the same color(e.g., G) including one photographic element 11 between the phasedifference detection element pairs 31. For example, in FIG. 10, highresolution photographic image data is generated by interpolating pixelinformation in a position of the first phase difference detectionelement 12 a based on the pixel information read from the threephotographic elements 11 a, 11 b, and 11 c as well as by interpolatingpixel information in a position of the second phase difference detectionelement 12 b based on the pixel information read from the threephotographic elements 11 d, 11 e, and 11 f.

Note that the present embodiment describes an example in which aphotographic element 11 is arranged one by one between the same type ofphase difference detection elements (between 12 a and 12 a, or 12 b and12 b), but the presently disclosed subject matter is not limited to thisexample. For example, the presently disclosed subject matter may includevarious arrangement embodiments in which one or more photographicelements 11 having a color filter of a specific color are arrangedbetween the phase difference detection element pairs 31. Further, thepresent embodiment describes the horizontal direction H as the phasedifference detection direction, but the presently disclosed subjectmatter may also apply to the vertical direction V as the phasedifference detection direction. Furthermore, the present embodimentdescribes an element array with a Bayer array, but the presentlydisclosed subject matter may also apply to a honeycomb configuration.

Next, an imaging unit 42 according to a seventh embodiment will bedescribed. The present embodiment further restricts an arrangement of apair of the phase difference detection elements 12 according to thesixth embodiment, and thus what has been described in the first to sixthembodiments will be omitted here.

FIG. 11 is a plan view illustrating an element arrangement of an imagingunit 42 according to the present embodiment. As illustrated in FIG. 11,phase difference detection element pairs 31 according to the presentembodiment are arranged in a staggered pattern. More specifically, aplurality of phase difference detection element pairs 31 are arranged inan alternating pattern between a first pixel pair column 311 in whichthe plurality of phase difference detection element pairs 31 arearranged in the horizontal direction H and a second pixel pair column312 in which the plurality of phase difference detection element pairs31 are arranged in the horizontal direction H.

Next, an imaging unit 42 according to an eighth embodiment will bedescribed. The present embodiment restricts an arrangement of the phasedifference detection element 12 according to any one of the first tofifth embodiments, and thus what has been described in the first tofifth embodiments will be omitted here.

FIG. 12 is a plan view illustrating an element arrangement of an imagingunit 42 according to the present embodiment. As illustrated in FIG. 12,in the present embodiment, a phase difference detection element pair 33a having a mutually adjacent pair of the first phase differencedetection elements 12 a and a phase difference detection element pair 33b having a mutually adjacent pair of the second phase differencedetection elements 12 b are arranged in an array pattern along thehorizontal direction H which is a phase difference detection direction.

According to the present embodiment, when the focus detection unit (51in FIG. 1) performs focus detection, the pixel information read from apair of photodiodes 18 is synthesized for each of the phase differencedetection element pairs 33 a and 33 b, and defocus amount is calculatedbased on the synthesized pixel information. Briefly, pixel informationsynthesis (pixel mixing) is performed on the two phase differencedetection elements 12 a and 12 b for each phase difference detectionelement pair.

Next, an imaging unit 42 according to a ninth embodiment will bedescribed. The present embodiment further restricts an arrangement of apair of the phase difference detection elements 12 according to theseventh embodiment, and thus what has been described in the first toseventh embodiments will be omitted here.

FIG. 13 is a plan view illustrating an element arrangement of an imagingunit 42 according to the present embodiment. As illustrated in FIG. 13,according to the present embodiment, phase difference detection elementpairs 31 having a mutually adjacent arrangement of the first phasedifference detection element 12 a and the second phase differencedetection element 12 b are arranged along a mutually orthogonal firstdirection (horizontal direction H in the present embodiment) and asecond direction (vertical direction V in the present embodiment); andan arrangement pitch between the phase difference detection elementpairs 31 in the first direction H for phase difference detection isequal to or less than the arrangement pitch between the phase differencedetection element pairs 31 in the second direction V for pixel mixing.

The present embodiment provides a column pair 35 including a column 34 aof the first phase difference detection element 12 a and a column 34 bof the second phase difference detection element 12 b along the seconddirection V, and arranges a plurality of the column pairs 35 in thefirst direction H.

According to the present embodiment, when the focus detection unit (51in FIG. 1) performs focus detection, pixel information is synthesizedbetween a plurality of the first phase difference detection elements 12a arranged along the second direction as well as pixel information issynthesized between a plurality of the second phase difference detectionelements 12 b arranged along the second direction, and defocus amount iscalculated based on the synthesized pixel information. Briefly, pixelinformation synthesis is performed for each column 34 a of the firstphase difference detection elements 12 a and for each column 34 b of thesecond phase difference detection elements 12 b.

Note that the presently disclosed subject matter is not limited to theimaging unit described using FIGS. 10 to 13. The presently disclosedsubject matter can be applied to a double faced imaging unit including asurface “A” and a surface “B” capable of controlling imaging mutuallyindependently. Such a double face configuration enables mutuallyindependent charge accumulation control and reading control. Morespecifically, switching can be easily performed between a high dynamicrange photography in which the surface “A” and the surface “B” areexposed with different exposure time, photographic pixel information ofthe surface “A” is synthesized with photographic pixel information ofthe surface “B”, and a high dynamic range imaging image is acquired andrecorded; and a high resolution photography in which the surface “A” andthe surface “B” are exposed with the same exposure time and highresolution imaging image including photographic pixel information of thesurface “A” and the surface “B” is acquired and recorded.

FIG. 14 is a plan view illustrating an example of a double facedhoneycomb configuration. The following description focuses on what isdifferent from the imaging unit 42 illustrated in FIGS. 10 to 13.

In FIG. 14, an uppercase character R, G, or B designates a photographicelement (11 in FIG. 2) on the surface “A”; a lowercase character r, g,or b designates a photographic element (11 in FIG. 2) on the surface“B”; P_(A) designates a phase difference detection element (12 a or 12 bin FIG. 2) on the surface “A”; and P_(B) designates a phase differencedetection element (12 a or 12 b in FIG. 2) on the surface “B”. Further,R or r designates an element with a red color filter; G or g designatesan element with a green color filter; and B or b designates an elementwith a blue color filter. Note that each of the phase differencedetection elements P_(A) and P_(B) according to the present embodimentis an element with a green color filter.

According to the present embodiment, a group of pixels R, G, B, P_(A) onthe surface “A” is arranged in a square lattice; a group of pixels r, g,b, P_(B) on the surface “B” is arranged in a square lattice as well asat an inter-lattice position of a pixel group on the surface “A”, whichprovides a honeycomb configuration as a whole. The honeycombconfiguration is such that elements in odd rows are shifted by ½ pixel(element) pitch from elements in even rows.

In such an imaging unit, a pair of phase difference detection elementsP_(A) and P_(B) is arranged in an array pattern along the horizontaldirection and the vertical direction.

FIG. 15 illustrates an interpolation of photographic pixel informationin a position of the phase difference detection element P_(A) on thesurface “A”. FIG. 16 illustrates an interpolation of photographic pixelinformation in a position of the phase difference detection elementP_(B) on the surface “B”. As illustrated in FIG. 15, with a focus onlyon the imaging elements on the surface “A”, four photographic elementshaving a color filter of the same color (G in the present embodiment)are arranged adjacent to each phase difference detection element P_(A).When the image data generation unit (53 in FIG. 1) interpolatesphotographic pixel information in a pixel position of each phasedifference detection element P_(A), the image data generation unit usespixel information of four photographic elements which are adjacent toeach phase difference detection element P_(A) on the surface “A” andhave a color filter of the same color. As illustrated in FIG. 16, alsoon the surface “B”, four photographic elements having a color filter ofthe same color (G in the present embodiment) are arranged adjacent toeach phase difference detection element P_(B). Like on the surface “A”,the image data generation unit interpolates photographic pixelinformation in a pixel position of each phase difference detectionelement P_(B).

FIG. 17 is a plan view illustrating an example of a double faced Bayerarray. The element arrangement illustrated in FIG. 17 is different fromthe element arrangement illustrated in FIG. 14 in that FIG. 17 uses aBayer array, whereas FIG. 14 uses a honeycomb configuration. However,the element arrangement illustrated in FIG. 17 is the same as theelement arrangement illustrated in FIG. 14 in that a pair of phasedifference detection elements P_(A) and P_(B) is arranged in an arraypattern along the horizontal direction and the vertical direction. FIG.18 illustrates an interpolation of photographic pixel information in aposition of the phase difference detection element P_(A) on the surface“A”. FIG. 19 illustrates an interpolation of photographic pixelinformation in a position of the phase difference detection elementP_(B) on the surface “B”. As illustrated in FIGS. 18 and 19, on each ofthe surfaces “A” and “B”, four photographic elements having a colorfilter of the same color (G in the present embodiment) are arrangedadjacent to each of the phase difference detection elements P_(A) andP_(B). When the image data generation unit (53 in FIG. 1) interpolatesphotographic pixel information in a pixel position of each of the phasedifference detection elements P_(A) and P_(B), the image data generationunit uses pixel information of four photographic elements which areadjacent to each of the phase difference detection elements P_(A) andP_(B) and have a color filter of the same color.

Note that the double faced element arrangement illustrated in FIGS. 14and 17 are just an example and as described in FIG. 11, the elementarrangement may be such that phase difference detection element pairsare arranged in a staggered pattern. Further, as described in FIG. 12,the element arrangement may be such that the first phase differencedetection element pair having a mutually adjacent pair of the firstphase difference detection elements (12 a in FIG. 2) and the secondphase difference detection element pair having a mutually adjacent pairof the second phase difference detection elements (12 b in FIG. 2) arearranged in an array pattern. Furthermore, as described in FIG. 13, thearrangement pitch may be such that the arrangement pitch between thephase difference detection element pairs in the horizontal direction forphase difference detection is equal to or less than the arrangementpitch between the phase difference detection element pairs in thevertical direction for pixel mixing.

Hereinafter, a method of manufacturing the imaging unit 42 will bebriefly described by referring to FIG. 3.

First, the semiconductor substrate 101 is prepared. Then, thephotodiodes 17, 18 a, and 18 b, the vertical charge transfer path 19,and the like are formed on the semiconductor substrate 101. Here, thephotodiodes 17, 18 a, and 18 b may be formed with the same shape andsize for photographing and for phase difference detection.

Then, the light shielding film 102 is formed on the semiconductorsubstrate 101. Here, the light shielding film 102 is formed on a regionseparating between the photodiodes 17, 18 a, and 18 b, and an opening isformed on each of the photodiodes 17, 18 a, and 18 b.

Then, the insulating film 103, the lens layer 104, and the flat layer105 are formed on the semiconductor substrate 101 and the lightshielding film 102. The lens layer 104 can be formed by patterning. Notethat in FIG. 3, as the inner microlenses 15, 16 a, and 16 b, both of aconvex entrance lens on an upstream side of the optical path and aconvex exit lens on a downstream side of the optical path are formed,but only the entrance lens may be formed.

Then, the color filter layer 106 is formed on the flat layer 105. Notethat FIGS. 10 to 13 illustrate an example in which a color filter of G(green) is formed as the color filter of the phase difference detectionelements 12 a and 12 b, but a color filter of other color may be formed.Further, the phase difference detection elements 12 a and 12 b may betransparent without using a color filter.

Thus, the laminated structure 110 is configured except the topmicrolenses 13, 14 a, and 14 b.

Then, the top microlenses 13, 14 a, and 14 b are formed by patterning onan uppermost surface (on the color filter layer 106 according to thepresent embodiment) of the laminated structure 110. Here, according tothe above described third embodiment, switching between forming the topmicrolenses 14 a and 14 b for phase difference detection and formingonly the top microlens 13 for photographing can be performed byswitching the photo mask at patterning.

FIG. 20 is a schematic flowchart illustrating a flow of an example of aphotographing process of the digital camera 100 in FIG. 1. This processis executed according to a program by the CPU 50 in FIG. 1.

First, in step S1, focus detection by phase difference detection methodis performed. More specifically, the imaging unit 42 is used to take animage under the control of the imaging control unit 43. Then, the focusdetection unit 51 detects defocus amount by detecting a phase differencebetween the pixel information read from the photodiodes 18 a of aplurality of the first phase difference detection elements 12 a and thepixel information read from the photodiodes 18 b of a plurality of thesecond phase difference detection elements 12 b.

Note that when an arrangement pitch between the phase differencedetection elements 12 a and 12 b increases, it is preferable to performpixel mixing in this step to ensure low intensity performance. Forexample, for the imaging unit 42 according to the eighth embodimentillustrated in FIG. 12, pixel mixing is performed on the first phasedifference detection element pair 33 a as well as pixel mixing isperformed on the second phase difference detection element pair 33 b.For example, for the imaging unit 42 according to the ninth embodimentillustrated in FIG. 13, pixel mixing is performed on a column 34 a ofthe first phase difference detection element 12 a as well as pixelmixing is performed on a column 34 b of the second phase differencedetection element 12 b. In the pixel mixing, pixel information read fromthe same type and a plurality of phase difference detection elements 12is synthesized. According to such pixel mixing, even a low densityarrangement of phase difference detection elements 12 can suppressreduction in focus detection precision.

Then, in step S2, focusing is performed based on the focus detectionresults. More specifically, the focusing control unit 52 uses the lensdrive unit 41 to move the focus lens by the moving amount correspondingto the defocus amount as needed. In other words, the focus lens is movedto a focusing lens position until the defocus amount reaches 0 (zero).

Then, in step S3, photographic image data is acquired. Morespecifically, the imaging unit 42 is used to take an image under thecontrol of the imaging control unit 43. Then, the image data generationunit 55 generates photographic image data based on the pixel informationread from the photodiodes 17 of a plurality of photographic elements 11.

It is preferable to interpolate pixel information in this step in orderto improve image quality of the photographic image data. For example,for the imaging unit 42 according to the sixth embodiment illustrated inFIG. 10, high quality photographic image data is generated byinterpolating pixel information for photographic image data generationin a position of each of the phase difference detection elements 12 aand 12 b based on pixel information of the adjacent photographicelements 11 a to 11 f for each of the phase difference detectionelements 12 a and 12 b.

Then, in step S4, photographic image data is recorded. Morespecifically, the recording medium control unit 63 records thephotographic image data in the recording medium 64.

Note that the imaging unit 42 is not particularly limited to a CCDimaging device, but may be a CMOS imaging device.

It is to be understood that the presently disclosed subject matter isnot limited to the examples described in this description and theexamples illustrated in the accompanying drawings, and various designchanges and improvements can be made to the presently disclosed subjectmatter without departing from the spirit and scope of the presentlydisclosed subject matter.

1. An imaging device comprising an arrayed imaging element groupconfigured to receive light passing through a photographic lens, whereinthe imaging element group includes a plurality of photographic elementsused for photographic image data generation and a plurality of phasedifference detection elements used for phase difference detection forfocus detection of the photographic lens, each of the photographicelements and each of the phase difference detection elements include: anon-chip microlens configured to collect light passing through thephotographic lens; a photoelectric conversion element configured toreceive the light passing through the on-chip microlens; and an internalmicrolens disposed between the on-chip microlens and the photoelectricconversion element, the photographic element is configured such that anoptical axis of the on-chip microlens matches an optical axis of theinternal microlens, and the phase difference detection element isconfigured such that the optical axis of the on-chip microlens isshifted from the optical axis of the internal microlens.
 2. The imagingdevice according to claim 1, wherein both the photographic element andthe phase difference detection element are configured such that theoptical axis of the internal microlens matches the optical axis of thephotoelectric conversion element.
 3. An imaging device comprising anarrayed imaging element group configured to receive light passingthrough a photographic lens, wherein the imaging element group includesa plurality of photographic elements used for photographic image datageneration and a plurality of phase difference detection elements usedfor phase difference detection for focus detection of the photographiclens, each of the photographic elements and each of the phase differencedetection elements include: an on-chip microlens configured to collectlight passing through the photographic lens; a photoelectric conversionelement configured to receive the light passing through the on-chipmicrolens; and an internal microlens disposed between the on-chipmicrolens and the photoelectric conversion element and have an entrancelens on an upstream side of an optical path and an exit lens on adownstream side of the optical path, the photographic element isconfigured such that an optical axis of the entrance lens of theinternal microlens matches an optical axis of the exit lens, and thephase difference detection element is configured such that the opticalaxis of the entrance lens of the internal microlens is shifted from theoptical axis of the exit lens.
 4. The imaging device according to claim3, wherein both the photographic element and the phase differencedetection element are configured such that the optical axis of the exitlens of the internal microlens matches the optical axis of thephotoelectric conversion element.
 5. The imaging device according toclaim 1, wherein the photoelectric conversion element of the phasedifference detection element has the same shape as that of thephotoelectric conversion element of the photographic element.
 6. Theimaging device according to claim 1, wherein the on-chip microlens ofthe phase difference detection element has a smaller diameter than thediameter of the on-chip microlens of the photographic element.
 7. Theimaging device according to claim 6, further comprising a lightshielding unit around the on-chip microlens of the phase differencedetection element.
 8. The imaging device according to claim 1, furthercomprising a first and a second of the phase difference detectionelements configured to generate pixel information corresponding to lightpassing through mutually different partial regions of the exit pupil ofthe photographic lens, wherein a mutually adjacent pair of elementsincluding the first and the second of the phase difference detectionelements is arranged in an array pattern.
 9. The imaging deviceaccording to claim 8, wherein three or more of the photographic elementshaving a color filter of the same color are arranged adjacent to each ofthe phase difference detection elements.
 10. The imaging deviceaccording to claim 1, further comprising a first and a second of thephase difference detection elements which generate pixel informationcorresponding to light passing through mutually different partialregions of the exit pupil of the photographic lens, wherein a mutuallyadjacent element pair including the first and second phase differencedetection elements is arranged in a staggered pattern.
 11. The imagingdevice according to claim 1, further comprising a first and a second ofthe phase difference detection elements configured to generate pixelinformation corresponding to light passing through mutually differentpartial regions of the exit pupil of the photographic lens, wherein afirst element pair having a mutually adjacent pair of the first phasedifference detection elements and a second element pair having amutually adjacent pair of the second phase difference detection elementsare arranged in an array pattern.
 12. The imaging device according toclaim 1, further comprising a first and a second of the phase differencedetection elements configured to generate pixel informationcorresponding to light passing through mutually different partialregions of the exit pupil of the photographic lens, wherein a mutuallyadjacent element pair including the first and second phase differencedetection elements is arranged in an array pattern along a firstdirection for detecting phase difference and a second direction forsynthesizing the pixel information, and an arrangement pitch of theelement pair in the first direction is equal to or less than arrangementpitch of the element pair in the second direction.
 13. An electroniccamera comprising: the imaging device according to claim 1; a focusdetection device configured to perform focus detection of thephotographic lens based on pixel information read from the phasedifference detection element; a focusing control device configured toperform focusing of the photographic lens based on a focus detectionresult of the focus detection device; and an image data generationdevice configured to generate photographic image data based on pixelinformation read from the photographic element.
 14. An electronic cameracomprising: the imaging device according to claim 3; a focus detectiondevice configured to perform focus detection of the photographic lensbased on pixel information read from the phase difference detectionelement; a focusing control device configured to perform focusing of thephotographic lens based on a focus detection result of the focusdetection device; and an image data generation device configured togenerate photographic image data based on pixel information read fromthe photographic element.
 15. An electronic camera comprising: theimaging device according to claim 9; a focus detection device configuredto perform focus detection of the photographic lens based on pixelinformation read from the phase difference detection element; a focusingcontrol device configured to perform focusing of the photographic lensbased on a focus detection result of the focus detection device; and animage data generation device configured to generate photographic imagedata based on pixel information read from the photographic element, andgenerate the photographic image data by interpolating photographic pixelinformation in a position of each of the phase difference detectionelements based on pixel information read from the photographic elementwhich is arranged adjacent to each of the phase difference detectionelements and has the color filter of the same color.
 16. An electroniccamera comprising: the imaging device according to claim 10; a focusdetection device configured to perform focus detection of thephotographic lens based on pixel information read from the element pairincluding the first and second phase difference detection elements; afocusing control device configured to perform focusing of thephotographic lens based on a focus detection result of the focusdetection device; and an image data generation device configured togenerate photographic image data based on pixel information read fromthe photographic element.
 17. An electronic camera comprising: theimaging device according to claim 11; a focus detection deviceconfigured to synthesize pixel information read from a pair of thephotoelectric conversion elements for each of the element pairs, andperform focus detection of the photographic lens based on synthesizedpixel information, a focusing control device configured to performfocusing of the photographic lens based on a focus detection result ofthe focus detection device; and an image data generation deviceconfigured to generate photographic image data based on pixelinformation read from the photographic element.
 18. An electronic cameracomprising: the imaging device according to claim 12; a focus detectiondevice configured to synthesize pixel information of the photoelectricconversion elements between a plurality of the first phase differencedetection elements arranged along the second direction, synthesize pixelinformation of the photoelectric conversion elements between a pluralityof the second phase difference detection elements arranged along thesecond direction, and perform focus detection of the photographic lensbased on synthesized pixel information, a focusing control deviceconfigured to perform focusing of the photographic lens based on a focusdetection result of the focus detection device; and an image datageneration device configured to generate photographic image data basedon pixel information read from the photographic element.